Study On Vibration Damping Performance Of Composite Crankshaft Torsional Vibration Damper

When the engine shaft is running,it will produce a kind of torsional vibration.This kind of torsional vibration will affect the performance of the engine.In severe cases,it will cause the engine to stop working.To reduce the torsional vibration of the crankshaft of the engine,a torsional vibration damper is often installed at the front end of the crankshaft.At present,there are few researches on crankshaft dampers.Most of them use traditional experience design and experiments to repeatedly modify the drawing size and technology to improve the damping performance of shock absorbers.The purpose of this paper is to study the crankshaft torsional vibration damper from the aspects of structural design,vibration damping theory analysis,software simulation analysis,machining process design and experimental verification of silicone oil-rubber composite crankshaft vibration damper.Research provides reference.The main work of this thesis is as follows:1.Through the vibration analysis of engine crankshaft,it is concluded that the vibration frequency of crankshaft under undamped free vibration is simple harmonic vibration with constant amplitude,and the forced vibration frequency of crankshaft under damped forced vibration is related to the interference frequency.The amplitude of the crankshaft is related to the exciting frequency,the moment of inertia and the coefficient of flexibility of the crankshaft,the moment of inertia of the absorber and the coefficient of compliance.The performance parameters and main structural dimensions of silicone oil shock absorber and rubber isolator are calculated,and the engineering drawings of the shock absorber are drawn.2.The damping force of silicon oil absorber is calculated by studying the properties of silicon oil material,and the relation diagram between amplitude and exciting frequency is obtained by studying the damping force of silicon oil absorber.The damping value of the optimum damping point,the exciting frequency value and the crankshaft amplitude value of the optimum damping point are calculated,and the rubber constitutive model is studied,and the resonance curve is obtained by the vibration absorption analysis of the rubber isolator.The optimum damping point and damping value are obtained according to the relation of exciting frequency.3.In this thesis,the model is established by UG NX software,and the static torsional stiffness of rubber isolator is simulated by ANSYS software.The maximum deformation and equivalent maximum stress under the corresponding load are obtained.The first 20 order vibration modes and frequencies of the first 20 order shock absorbers are obtained.The fatigue simulation analysis of the absorber obtains the minimum life area and minimum life time.The results of the simulation analysis all meet the design requirements.4.In this thesis,the processing technology of silicone oil-rubber compound crankshaft torsional shock absorber is designed,including the spinning forming process of multi-wedge pulley,the finishing processing and heat treatment of metal parts,the degreasing and sand blasting of metal parts in rubber vibration isolator.According to the requirements of properties,the formulation of natural rubber and the technological parameters of rubber parts vulcanization are given,and the process parameters of rubber vulcanization are optimized by Moldflow software,and the filling time of vulcanization is obtained.The optimum process parameters,such as curing time and temperature,have been designed,such as assembly of silicon oil shock absorber,electron beam welding,adding silicon oil and so on.Parameters,and silicone oil-rubber compound torsional shock absorber assembly process.5.The maximum torsional moment of rubber parts is obtained by static torsional stiffness test of rubber isolator,the resonance frequency value and the amplitude value of crankshaft are obtained by the resonance frequency test of compound torsional shock absorber.The durability test simulates the wear and failure phenomena of various parts in the actual working environment by simulating the compound crankshaft torsional shock absorber and verifies that the test results meet the requirements of the test.Through the research of this subject,the mechanical structure of silicone oil rubber compound crankshaft torsional shock absorber is designed,the engineering diagram is drawn,the relationship diagram of crankshaft amplitude and exciting frequency is studied,and the damping value of optimum damping point is calculated.The model of compound crankshaft shock absorber is established,and the static torsional stiffness and deformation,modal frequency,mode shape and fatigue life are simulated and analyzed.The processing technology and related parameters of the silicone oil-rubber composite damper are designed.The experimental results show that the optimum damping value is achieved and the experimental results meet the design requirements.